Screening blood donations for Zika proved costly, low yield

Major finding: Testing confirmed only 8 authentic cases and cost nearly $42 million over 15 months.

Study details: Screening and confirmatory testing of 4,325,889 donations of blood in the United States during 2016-2017.

Disclosures: American Red Cross and Grifols Diagnostic Solutions provided funding. Grifols makes a test used in the study. Dr. Saá disclosed research support from Grifols but had no other conflicts of interest.

Nonetheless, “actual and perceived risks to the blood supply seem to be conflated,” the experts wrote. They noted that the United States currently has no active areas of Zika virus transmission and that confirmed mosquito-borne, locally acquired infections fell from 226 in 2016 to two the following year.

There is no historical precedent for ending a policy of testing blood donations for pathogens, they added. Consequently, ending widespread screening “may actually prove to be far more challenging than the decision to start.” For now, a precautionary, risk-based approach should entail “continuous review” of screening policies and “reassessment as new data emerge.”

The editorialists are with Johns Hopkins University and Johns Hopkins University’s Bergman Institute of Bioethics, both in Baltimore. They reported having no relevant conflicts of interest. These comments are from their editorial (New Engl J Med. 2018;378:19:1837-41).

FROM THE NEW ENGLAND JOURNAL OF MEDICINE

Testing donated blood for Zika virus in the United States confirmed just 8 authentic cases and cost nearly $42 million over a period of 15 months, investigators reported online May 10 in the New England Journal of Medicine.

That price did not reflect a commercial price hike, said Paula Saá, PhD, of the American Red Cross in Gaithersburg, MD, and her associates. Furthermore, more than half of the Zika cases had a low viral level that might not be infectious.

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Maternal-fetal Zika transmission can be devastating, and infections have been detected in asymptomatic blood donors. Therefore, in 2016, the Food and Drug Administration began recommending screening of blood donations. In response, the American Red Cross started screening pooled donations for Zika RNA by using a transcription-mediated amplification (TMA) test. Later in 2016, the FDA began recommending individually screening all blood donations; the Red Cross complied. For the study, Dr. Saá and her coinvestigators analyzed pooled and individual tests from a 15-month period during 2016-2017.

Among more than 4 million screened donations, 9% were tested in pools. All pooled tests were negative. The other 3.9 million donations were screened individually. Only 160 were positive, and just 6 were confirmed positive on repeat TMA. Two of these six confirmed positives also were RNA-positive on reverse transcription polymerase chain reaction, while two were equivocal and two were negative. The positive and equivocal donations were negative for Zika immunoglobulin M on enzyme-linked immunosorbent assay, which indicated acute infections. The RNA-negative infections were IgM-positive, indicating prior infections.

Three more donations were initially positive on TMA, were negative on repeat TMA, and were IgM-positive, bringing the total case count to nine. Among these, two donors had been infected in Florida, six had traveled to Zika-endemic areas, and one had received an experimental Zika vaccine, according to the researchers.

For each detection of authentic Zika virus RNA infection in U.S.-donated blood, testing had cost $5.3 million, they concluded. They called the current FDA recommendation to individually screen all U.S. blood donations for Zika virus “low-yield” and “high cost.” Of three acute infections with enough sample left for pooled testing, all were positive, they noted.

The American Red Cross and Grifols Diagnostic Solutions provided funding. Dr. Saá disclosed research support from Grifols, which makes the TMA test used in the study. She had no other conflicts of interest.